Testing equipment



March 26, 1940. w. Y. LANG TESTING EQUIPMENT Filed April 29, 1959 2 Sheets-Sheet l /Nl E/VTOR W L LANG A T TORNE V Filed April 29, 1939 2 Sheets-Sheet 2 MARKING BIAS SPACING BIAS F/GIZ SPACING END DISTORTION 0 V5 CAMS PERMANE TO TRANS TENCE IN NTLY CUT MIT TEST $EN FIVE UNIT STOP- START PERMUTATION CODE A SPACE MARK SPACE MARK SPACE MARK MARK MARKING BIAS SPACING BIAS SPACING END DISTORTION MARKING END DISTORTION BCDE lNVE/VTOR W I. LANG Patented Mar.26,'l940 i UNITED STATES PATENT OFFICE 2,194,7o5;" j I "TESTING EQUIPMENT j p i Wilmarth'Y. Lang, Towaco, N. 1., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y.,-a corporation ofNe'w York A iio t enA rirza 1939, Serial No. 270,768 scams. 173-69) This invention relates to improved testing to subject it to both marking and spacing bias equipment to'be used for observing the capabiland marking and spacing end distortion. ities of telegraph receiving apparatus when op- In tests using enddistortion, it has been found erated by distorted signals and is an improvethat a receiving unit which would tolerate a i ment on the testing equipment formingthe s'ubgiven amount of bias would. fail on the same 5 ject-matter of my Patent No. 2,036,059, issued amount of end distortion. Also, the optimum March 31, 1936. i settings for bias and end distortionwere not the The object of my inventionis to provide means same. Further study of this condition disclosed for producing distorted signals affected in a that the separation of the optimum settings for number of ways all characteristic of start-stop bias and end distortion was equal tothe internal 10 working. i biasof the teletypewriter, that is, the bias pres-I Specific to this art is that type of distortion ent in the machine due to manufacturing varia'-' spoken of as loias and that type of distortion tions and adjustmentswhich prevent it from respoken of as end distortion or end displacement. ceiving correctly signals distorted: with fifty per" 16 Bias is the advance or delay of the beginning of cent marking or fifty per cent spacing distortion 16' all marking impulses with respect tothe beginat asingle settin f the range finder arm." ning of the start impulse, and end distortion The theoretically perfect teletypewriter has an is the advance or delay of the ends of selecting orientation range of one hundred percent, that marking impulses with respect to the beginning is, Will receive Correct S ove t e full 20 of the start impulse. Expressed in another way, length of a standard transmitting impulse. Also, 20 it may be said thatin marking bias andimarking it will receive at the mid-point of its orientation end distortion the marking pulse is elongated; ran e signals distorted 1D to fifty P Ce a in the case of bias," the elongation occurs at the 5 fi y P nt Sp irrespectivefof h beginning of the marking pulse while in the case i type of distortion, Whether bias, end d of end distortion, the elongation occurs at the characteristic distortion, or fortuitous distortion. 25"

end of the marking pulse. In spacing bias and Using bias alone in testing of teletypewriters spacing end distortion, the marking pulse is shortallows setting up theoretically the ou of ened;' in the case of bias, the shortenin occurs internal bias and end distortion which the tele-' t t beginning of the marking pulse while in typewriter will tolerate. However, these calcula 3 the case of end distortion,-the shortening occurs tions arebased on the theoretica y p te1e atthe end of the marking pulse.lBias affects typewriter, s the stop pulse as well as all other marking pulses Using end distortion as well as bias, it is poswhereas end distortion affectsonly the selecting Sib e f0 determine y actual ements: the pulses-not thestop pulse. 1 i amount ofinternal bias present in the selector The object of this invention is, therefore, to mechanism and the type of internal bias-wheth- 35 provide means for transmitting toapparatus to ar v or pa e-ed these ad gs be tested impulses affected in varying degrees it is possible to determine the remedial measures by marking bias, spacingbias, marking end dis necessary to reduce the internal bias to the limits tortion, or spacing end distortion and to quickwhich have been determined as satisfactory for 40 ly change from one to the other, normal teletypewriter operation. e

The use of what is here defined as marking A feature of the present invention is a testing and spacing bias for testing teletypewriters will equ pm t having d d t y va le see show up errors in adjustments and inaccuracies mented rings for producing a of the o yp inthe manufacture of parts. However, teletypa of distortion described between zero and fifty per writers which are apparently satisfactory from" cent distortion and means for quickly switching 45' the standpoint of this type of distortion will still from O to t e o I be'not wholly satisfactory until tested and ad The drawin s o st of w ets, thafilst justed under conditions caused by that other type f wh h a s eshowing a p rsp ve of distortion here known as end distortion. In view of the testing equipment, and the second 5 other words, itis known that teletypewriters reof which contains Fig. 2, showing a circuit dia- .50

spond somewhat differently to the lengthening or ram o the e ec cal n ect o s a d a schshortening of the marking pulses when, the bematic diagram of the moving parts of the test ginning of the impulse is affected than when ing equipment, and Fig. 3, showingan explanatheend of the impulse is affected. Hence, it is tory diagram for illustrating the various kinds of a necessary, in order to fully test a-teletypewriter, distortiondescribed. Fig. 3 is so placedwithr'e 55 spect to Fig. 2 that the distortion of the signals can easily be understood from the description of the movement of the above-noted movable segmented rings. I

Referring both to Fig. 1 and the schematic part of Fig. 2, it will be seen that a constant speed motor lv drives a worm 2 and gear 3 whereby the shaft 5 is moved constantly in a counterclockwise direction. Another'worrn 5 fixed to the shaft 4 meshes with a gear '6 which, in turn, drives a pinion l meshed. with a gear 8. The gear 5 and the pinion 1 cannot be seen in the perspective view of Fig. l but the manner in which gear 8 is driven'will be apparent from the schematic diagram of Fig. 2. The gear 8'.drives a shaft 9 on which are fixed-five cams Ii, l2, l3, l4 and I5 which close contacts to operate relays i6, ll, I8,

l9 and 28, respectively. The camsare cut to op crate the relays in such a manner-that a test sentence, such as The quick brown fox'jumped over a lazy dogs back, will be transmitted re- 7 peatedly by the testing equipment. I

-At either end of the shaft 4 there is a set of hrushessuch as v9'! and 98. The, brush. set 9'! has four contacting members traveling over three segmented ringsand one solid ring. In Fig.2 these rings are developed so that the circuit arrangement may be easily explained. The brush as also has four contacting members wiping over one solid ring and three segmented rings in like manner. As indicated by the notes to the right of the two upper segmented rings and thetwo lower segmented rings; these are made movable in the direction indicated. The uppermost segmerited ring is that one movable by means of a knob lifi working a pinion Hi0 and causing the movement of the pinion of the ring through the meshing of the rack lill. As shown in Fig. l, the knob 99 carries an indicator Hi2 which cooperates witha scale N33 to indicate that the associated segmented ring has been moved from a position Where it will cause impulses from zero marking bias to fifty per cent marking bias to be transmitted. Likewise, the knob we causes the movement of the second row of segments and moves these so as to produce impulses having spacing bias between the limits of Zero and fifty (ill per cent. At the other end of the shaft 21. like distributor is adjusted by means of a knob HM to adjust marking end distortion. betweenthe limits of zero and fifty per cent and knob causes an adjustment for producing impulses having spacing end distortion between the limits of zero and fifty per cent.

As the various segmented rings. are indicated in Fig. 2, they are all placed at the position of zero bias or end distortion. The brushes 9"! and 98' move in a direction from left'to right and, as shown, are just at the point where they would be leaving the portion of the segments illustrated and starting in on their travels again at the extreme left.

shown, the equipment willsend impulses afiected by either spacing bias or spacing end distortion in accordance with the position of the key Hi. When the key 51 is depressed so that the alternate contacts of the various sets are made, then the equipment will transmit impulses aflected with marking bias or marking end distortion in accordance With the position of key H1.

Fig. 3 indicates the code for the letter Y affected invarious manners. The line A shows the various marking and spacing impulses'unaffected. The line B shows the impulses affected with marking bias. It will be noted here that the marking impulses l, 3 and 5 all start a little earlier than in the case of line B, whereas the spacing impulses start at the same time. In line C the impulses are affected with spacing bias. It will be noted that the marking impulses I, '3 and 5 in this case all start a little later than in the case of line A. In line D the impulses are affected with spacing end distortion and here it will be noted that the marking impulses I and 3 end a little sooner than in the case of line A. In line E the impulses are affected with marking end distortion and it will be noted that the marking impulses i and 3 end somewhat later than in the case of line A.

There are dot and dash lines drawn from Fig. 3 in the direction of Fig. 2 and similar lines from Fig. 2 drawn in the direction of Fig. '3.

This is to indicate that the various segments are be transmitted and the brushes 9? and 98 are sweeping over the contacts in a left-to-right direotion. Let us assume that the key iii is in the position shown and the key 51 is depressed so that impulses affected with marking bias will be transmitted.

Since the first impulse will be a marking impulse, a circuit may be traced from the teletypewriter generally indicated by the rectangle HMS and which may be assumed to be under test through the lower make contacts of the key ID, the solid ring 56, the brushes 9?, segment 22, the lower contact of contact set 63, the segment 45 and in parallel therewith the front contact and lowermost armature of relay l6, conductor I01, the make contact of the upper set of keys NJ to the teletypewriter I06. With the upper row of segments 2| to 21, inclusive, in the position shown, the marking impulse will be exactly the length of the impulse indicated as i in Fig. 3. If, however, the set of segments 2| to 21, inclusive, is moved toward'the left, then the marking impulse will be started somewhat earlier since the upper contact of the brush 8'! will come in contact with segment 22 prior to the dot and dash line indicating the normal start of impulse I. Since segments .22 and 45 are connected together through the key-set 63, this marking impulse will be elongated by the amount of the movement of the upper segments 2i to 27, inelusive.

If the key 5? is moved upward and to the position as shown, then key-set E3 will cause segments 3!) and 45 to be connected together and the marking impulse will be traced through ring 55 and first segment 33 and last segment 45. In the position as shown, the marking impulse will be of exact length for zero bias. If, however, the set of segments 28'to 4|, inclusive, is moved toward the right, then the marking impulse will start somewhat later and thus be shortened.

traced from the teletypewriter I06, through the lowercontacts thereof, the solid ring 68, thence through the brushes 36 to segment 9|, now connected through'the contacts of key-set E4 to segment l0 and thus to the front contact and outer upper armature of relay it to conductor H18 and thus to the upper contacts of key in and eventually back to the teletypewriter I06. With the segments til to 96, inclusive, as shown, the im pulses will be unaffected but if the segments are moved toward the right, then the impulses will be lengthened but the lengthening will take place at the end of the impulse, as indicated at line E of Fig. 3. e

With key it operated in its alternate position and key 577 as shown, the circuit may be traced from ring 68 through segments H1 and 82 which are connected by the key-set 64. and thence to the front contact and upper outer armature of With the segments relay 6 to conductor. H38. to 88, inclusive, as shown, the impulses will not be affected butif this row of segments is moved toward the left, as indicated, then the impulse will beshortened, as indicated in line D of Fig. 3. Here, also, in order to merge two marking impulses, one following the other. into one, a connection is made from segment H through the inner upper armature of relay E6 to segment 72 in a manner similar to that described above in connection with segment 46.

The various mechanical arrangements of the parts of the mounting of the'relays I 6 to 20 inclusive, of which onlyrelays i6 and 20 are shown, and the generaldesign of the machine will be apparent from the perspective view in Fig. 1. y

i What isclaimed is: M

1. In a teletypewriter communication system,

instrumentalities for testing the adjustment of receiving teletypewriter apparatus to correctly receive signals affected by bias and end distortion, said instrumentalities including in combination a transmitter-distributor provided with two segmented face-plates, means for enabling one of said segmented face-plates to transmit permutation code signals affected by bias, means for enabling the other of said segmented faceplates to transmit permutation codesignals affected by end ,distortion, and switching means for switching the transmitter-distributor from transmission. over one. of said face-plates to transmission over the oth erof said face-plates.

2. In a teletypewriter communication system,

'instrumentalities for testing the adjustment of receiving teletypewriter apparatus to correctly receive signals affected by bias and end distortion, said instrumentalities including in combination a transmitter-distributor provided with two segmented face-plates, each of said segmented face-plates having movable segmented rings, control means for-adjusting the positions of said movable segmented rings, said control means being individual to each face-plate, means for enabling one of said segmented face-plates to transmit permutation codesignals affected by variable amounts ofbias, means for enabling the other of said segmented face plates to transmit permutation code signals affected by variable amounts of end distortion, and switching means for switching the transmitter-distributor from transmission over one of said face-plates to transmission over the other of said face-plates. 3. A transmitterdistributor for repeatedly transmitting a test sentence in multiunit stopstart permutation code, comprising independent ly movable sets of commutator segments for affeoting the impulses of said codewith varying.

amounts of bias and end distortion and switching means for instantly changing the output of said transmitter-distributor.from one whose im pulses are affected with a given percentage of marking bias to one whose impulses are affected with another. given percentage of spacing bias or to one Whose impulses are affected with another given percentage of marking end distortion or to one whose impulses are affected with another given percentage of spacing end distortion.

4. A. transmitter-distributor for repeatedly transmitting at'est sentence in multiunit stopstart permutation code, comprising independently movable means to lengthen marking impulses at the beginning thereof, to lengthen marking impulses at the end thereof, to shorten marking impulses at the beginning thereof and to shorten marking impulses at the end thereof, and switching means for rendering atv one time any one of said independently movable means effective.

5. A transmitter-distributor for repeatedly transmitting a fixed test sentence in permutation code, comprising independently movable means for lengthening and shortening the marking impulses being transmitted and switching means for selecting variously affected transmission.

Y. LANG. 

